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/*
* Copyright 2010 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef skgpu_BufferWriter_DEFINED
#define skgpu_BufferWriter_DEFINED
#include "include/core/SkRect.h"
#include "include/private/SkColorData.h"
#include "include/private/SkNx.h"
#include "include/private/SkTemplates.h"
#include <type_traits>
namespace skgpu {
struct BufferWriter {
public:
// Marks a read-only position in the underlying buffer
struct Mark {
public:
Mark() : Mark(nullptr) {}
Mark(void* ptr, size_t offset = 0)
: fMark(reinterpret_cast<uintptr_t>(ptr) + offset) {
SkASSERT(ptr || offset == 0);
}
bool operator< (const Mark& o) const { return fMark < o.fMark; }
bool operator<=(const Mark& o) const { return fMark <= o.fMark; }
bool operator==(const Mark& o) const { return fMark == o.fMark; }
bool operator!=(const Mark& o) const { return fMark != o.fMark; }
bool operator>=(const Mark& o) const { return fMark >= o.fMark; }
bool operator> (const Mark& o) const { return fMark > o.fMark; }
ptrdiff_t operator-(const Mark& o) const { return fMark - o.fMark; }
explicit operator bool() const { return *this != Mark(); }
private:
uintptr_t fMark;
};
explicit operator bool() const { return fPtr != nullptr; }
Mark mark(size_t offset=0) const {
this->validate(offset);
return Mark(fPtr, offset);
}
protected:
BufferWriter() = default;
BufferWriter(void* ptr, size_t size) : fPtr(ptr) {
SkDEBUGCODE(fEnd = Mark(ptr, ptr ? size : 0);)
}
BufferWriter(void* ptr, Mark end = {}) : fPtr(ptr) {
SkDEBUGCODE(fEnd = end;)
}
BufferWriter& operator=(const BufferWriter&) = delete;
BufferWriter& operator=(BufferWriter&& that) {
fPtr = that.fPtr;
that.fPtr = nullptr;
SkDEBUGCODE(fEnd = that.fEnd;)
SkDEBUGCODE(that.fEnd = Mark();)
return *this;
}
// makeOffset effectively splits the current writer from {fPtr, fEnd} into {fPtr, p} and
// a new writer {p, fEnd}. The same data range is accessible, but each byte can only be
// set by a single writer. Automatically validates that there is enough bytes remaining in this
// writer to do such a split.
//
// This splitting and validation means that providers of BufferWriters to callers can easily
// and correctly track everything in a single BufferWriter field and use
// return std::exchange(fCurrWriter, fCurrWriter.makeOffset(requestedBytes));
// This exposes the current writer position to the caller and sets the provider's new current
// position to be just after the requested bytes.
//
// Templated so that it can create subclasses directly.
template<typename W>
W makeOffset(size_t offsetInBytes) const {
this->validate(offsetInBytes);
void* p = SkTAddOffset<void>(fPtr, offsetInBytes);
Mark end{SkDEBUGCODE(fEnd)};
SkDEBUGCODE(fEnd = Mark(p);)
return W{p, end};
}
void validate(size_t bytesToWrite) const {
// If the buffer writer had an end marked, make sure we're not crossing it.
// Ideally, all creators of BufferWriters mark the end, but a lot of legacy code is not set
// up to easily do this.
SkASSERT(fPtr || bytesToWrite == 0);
SkASSERT(!fEnd || Mark(fPtr, bytesToWrite) <= fEnd);
}
protected:
void* fPtr = nullptr;
SkDEBUGCODE(mutable Mark fEnd = {};)
};
/**
* Helper for writing vertex data to a buffer. Usage:
* VertexWriter vertices{target->makeVertexSpace(...)};
* vertices << A0 << B0 << C0 << ...;
* vertices << A1 << B1 << C1 << ...;
*
* Each value must be POD (plain old data), or have a specialization of the "<<" operator.
*/
struct VertexWriter : public BufferWriter {
inline constexpr static uint32_t kIEEE_32_infinity = 0x7f800000;
VertexWriter() = default;
// DEPRECATED: Prefer specifying the size of the buffer being written to as well
explicit VertexWriter(void* ptr) : BufferWriter(ptr, Mark()) {}
VertexWriter(void* ptr, size_t size) : BufferWriter(ptr, size) {}
VertexWriter(void* ptr, Mark end) : BufferWriter(ptr, end) {}
VertexWriter(const VertexWriter&) = delete;
VertexWriter(VertexWriter&& that) { *this = std::move(that); }
VertexWriter& operator=(const VertexWriter&) = delete;
VertexWriter& operator=(VertexWriter&& that) {
BufferWriter::operator=(std::move(that));
return *this;
}
VertexWriter makeOffset(size_t offsetInBytes) const {
return this->BufferWriter::makeOffset<VertexWriter>(offsetInBytes);
}
template <typename T>
struct Conditional {
bool fCondition;
T fValue;
};
template <typename T>
static Conditional<T> If(bool condition, const T& value) {
return {condition, value};
}
template <typename T>
struct Skip {};
template<typename T>
struct ArrayDesc {
const T* fArray;
int fCount;
};
template <typename T>
static ArrayDesc<T> Array(const T* array, int count) {
return {array, count};
}
template<int kCount, typename T>
struct RepeatDesc {
const T& fVal;
};
template <int kCount, typename T>
static RepeatDesc<kCount, T> Repeat(const T& val) {
return {val};
}
/**
* Specialized utilities for writing a four-vertices, with some data being replicated at each
* vertex, and other data being the appropriate 2-components from an SkRect to construct a
* triangle strip.
*
* - Four sets of data will be written
*
* - For any arguments where is_quad<Type>::value is true, a unique point will be written at
* each vertex. To make a custom type be emitted as a quad, declare:
*
* template<> struct VertexWriter::is_quad<MyQuadClass> : std::true_type {};
*
* and define:
*
* MyQuadClass::writeVertex(int cornerIdx, VertexWriter&) const { ... }
*
* - For any arguments where is_quad<Type>::value is false, its value will be replicated at each
* vertex.
*/
template <typename T>
struct is_quad : std::false_type {};
template <typename T>
struct TriStrip {
void writeVertex(int cornerIdx, VertexWriter& w) const {
switch (cornerIdx) {
case 0: w << l << t; return;
case 1: w << l << b; return;
case 2: w << r << t; return;
case 3: w << r << b; return;
}
SkUNREACHABLE;
}
T l, t, r, b;
};
static TriStrip<float> TriStripFromRect(const SkRect& r) {
return { r.fLeft, r.fTop, r.fRight, r.fBottom };
}
static TriStrip<uint16_t> TriStripFromUVs(const std::array<uint16_t, 4>& rect) {
return { rect[0], rect[1], rect[2], rect[3] };
}
template <typename T>
struct TriFan {
void writeVertex(int cornerIdx, VertexWriter& w) const {
switch (cornerIdx) {
case 0: w << l << t; return;
case 1: w << l << b; return;
case 2: w << r << b; return;
case 3: w << r << t; return;
}
SkUNREACHABLE;
}
T l, t, r, b;
};
static TriFan<float> TriFanFromRect(const SkRect& r) {
return { r.fLeft, r.fTop, r.fRight, r.fBottom };
}
template <typename... Args>
void writeQuad(const Args&... remainder) {
this->writeQuadVertex<0>(remainder...);
this->writeQuadVertex<1>(remainder...);
this->writeQuadVertex<2>(remainder...);
this->writeQuadVertex<3>(remainder...);
}
private:
template <int kCornerIdx, typename T, typename... Args>
std::enable_if_t<!is_quad<T>::value, void> writeQuadVertex(const T& val,
const Args&... remainder) {
*this << val; // Non-quads duplicate their value.
this->writeQuadVertex<kCornerIdx>(remainder...);
}
template <int kCornerIdx, typename Q, typename... Args>
std::enable_if_t<is_quad<Q>::value, void> writeQuadVertex(const Q& quad,
const Args&... remainder) {
quad.writeVertex(kCornerIdx, *this); // Quads emit a different corner each time.
this->writeQuadVertex<kCornerIdx>(remainder...);
}
template <int kCornerIdx>
void writeQuadVertex() {}
template <typename T>
friend VertexWriter& operator<<(VertexWriter&, const T&);
template <typename T>
friend VertexWriter& operator<<(VertexWriter&, const ArrayDesc<T>&);
};
template <typename T>
inline VertexWriter& operator<<(VertexWriter& w, const T& val) {
static_assert(std::is_pod<T>::value, "");
w.validate(sizeof(T));
memcpy(w.fPtr, &val, sizeof(T));
w = w.makeOffset(sizeof(T));
return w;
}
template <typename T>
inline VertexWriter& operator<<(VertexWriter& w, const VertexWriter::Conditional<T>& val) {
static_assert(std::is_pod<T>::value, "");
if (val.fCondition) {
w << val.fValue;
}
return w;
}
template <typename T>
inline VertexWriter& operator<<(VertexWriter& w, const VertexWriter::Skip<T>& val) {
w = w.makeOffset(sizeof(T));
return w;
}
template <typename T>
inline VertexWriter& operator<<(VertexWriter& w, const VertexWriter::ArrayDesc<T>& array) {
static_assert(std::is_pod<T>::value, "");
w.validate(array.fCount * sizeof(T));
memcpy(w.fPtr, array.fArray, array.fCount * sizeof(T));
w = w.makeOffset(sizeof(T) * array.fCount);
return w;
}
template <int kCount, typename T>
inline VertexWriter& operator<<(VertexWriter& w, const VertexWriter::RepeatDesc<kCount,T>& repeat) {
for (int i = 0; i < kCount; ++i) {
w << repeat.fVal;
}
return w;
}
template <>
SK_MAYBE_UNUSED inline VertexWriter& operator<<(VertexWriter& w, const Sk4f& vector) {
w.validate(sizeof(vector));
vector.store(w.fPtr);
w = w.makeOffset(sizeof(vector));
return w;
}
// Allow r-value/temporary writers to be appended to
template <typename T>
inline VertexWriter& operator<<(VertexWriter&& w, const T& val) { return w << val; }
template <typename T>
struct VertexWriter::is_quad<VertexWriter::TriStrip<T>> : std::true_type {};
template <typename T>
struct VertexWriter::is_quad<VertexWriter::TriFan<T>> : std::true_type {};
/**
* VertexColor is a helper for writing colors to a vertex buffer. It outputs either four bytes or
* or four float32 channels, depending on the wideColor parameter. Note that the GP needs to have
* been constructed with the correct attribute type for colors, to match the usage here.
*/
class VertexColor {
public:
VertexColor() = default;
explicit VertexColor(const SkPMColor4f& color, bool wideColor) {
this->set(color, wideColor);
}
void set(const SkPMColor4f& color, bool wideColor) {
if (wideColor) {
memcpy(fColor, color.vec(), sizeof(fColor));
} else {
fColor[0] = color.toBytes_RGBA();
}
fWideColor = wideColor;
}
size_t size() const { return fWideColor ? 16 : 4; }
private:
template <typename T>
friend VertexWriter& operator<<(VertexWriter&, const T&);
uint32_t fColor[4];
bool fWideColor;
};
template <>
SK_MAYBE_UNUSED inline VertexWriter& operator<<(VertexWriter& w, const VertexColor& color) {
w << color.fColor[0];
if (color.fWideColor) {
w << color.fColor[1]
<< color.fColor[2]
<< color.fColor[3];
}
return w;
}
///////////////////////////////////////////////////////////////////////////////////////////////////
struct IndexWriter : public BufferWriter {
IndexWriter() = default;
IndexWriter(void* ptr, size_t size) : BufferWriter(ptr, size) {}
IndexWriter(void* ptr, Mark end) : BufferWriter(ptr, end) {}
IndexWriter(const IndexWriter&) = delete;
IndexWriter(IndexWriter&& that) { *this = std::move(that); }
IndexWriter& operator=(const IndexWriter&) = delete;
IndexWriter& operator=(IndexWriter&& that) {
BufferWriter::operator=(std::move(that));
return *this;
}
IndexWriter makeOffset(int numIndices) const {
return this->BufferWriter::makeOffset<IndexWriter>(numIndices * sizeof(uint16_t));
}
void writeArray(const uint16_t* array, int count) {
size_t arraySize = count * sizeof(uint16_t);
this->validate(arraySize);
memcpy(fPtr, array, arraySize);
fPtr = SkTAddOffset<void>(fPtr, arraySize);
}
friend IndexWriter& operator<<(IndexWriter& w, uint16_t val);
};
inline IndexWriter& operator<<(IndexWriter& w, uint16_t val) {
w.validate(sizeof(uint16_t));
memcpy(w.fPtr, &val, sizeof(uint16_t));
w = w.makeOffset(1);
return w;
}
inline IndexWriter& operator<<(IndexWriter& w, int val) { return (w << SkTo<uint16_t>(val)); }
template<typename T>
inline IndexWriter& operator<<(IndexWriter&& w, const T& val) { return w << val; }
///////////////////////////////////////////////////////////////////////////////////////////////////
struct UniformWriter : public BufferWriter {
UniformWriter() = default;
UniformWriter(void* ptr, size_t size) : BufferWriter(ptr, size) {}
UniformWriter(void* ptr, Mark end) : BufferWriter(ptr, end) {}
UniformWriter(const UniformWriter&) = delete;
UniformWriter(UniformWriter&& that) { *this = std::move(that); }
UniformWriter& operator=(const UniformWriter&) = delete;
UniformWriter& operator=(UniformWriter&& that) {
BufferWriter::operator=(std::move(that));
return *this;
}
void write(const void* src, size_t bytes) {
this->validate(bytes);
memcpy(fPtr, src, bytes);
fPtr = SkTAddOffset<void>(fPtr, bytes);
}
};
} // namespace skgpu
#endif // skgpu_BufferWriter_DEFINED